Commit ef5e94af authored by Jeremy Fitzhardinge's avatar Jeremy Fitzhardinge Committed by Ingo Molnar
Browse files

x86_32: remove __PAGE_KERNEL(_EXEC) 


From: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>

Older x86-32 processors do not support global mappings (PGD), so must
only use it if the processor supports it.

The _PAGE_KERNEL* flags always have _PAGE_KERNEL set, since logically
we always want it set.

This is OK even on processors which do not support PGD, since all
_PAGE flags are masked with __supported_pte_mask before being turned
into a real in-pagetable pte.  On 32-bit systems, __supported_pte_mask
is initialized to not contain _PAGE_GLOBAL, and it is then added if
the CPU is found to support it.

The x86-32 code used to use __PAGE_KERNEL/__PAGE_KERNEL_EXEC for this
purpose, but they're now redundant and can be removed.

Signed-off-by: default avatarJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Cc: Stephen Tweedie <sct@redhat.com>
Cc: Eduardo Habkost <ehabkost@redhat.com>
Cc: Mark McLoughlin <markmc@redhat.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 8490638c

arch/x86/mm/init_32.c

+2 −8
Original line number Diff line number Diff line
@@ -383,11 +383,6 @@ static void __init set_highmem_pages_init(void) 
# define set_highmem_pages_init()	do { } while (0)

#endif /* CONFIG_HIGHMEM */



pteval_t __PAGE_KERNEL = _PAGE_KERNEL;

EXPORT_SYMBOL(__PAGE_KERNEL);



pteval_t __PAGE_KERNEL_EXEC = _PAGE_KERNEL_EXEC;



void __init native_pagetable_setup_start(pgd_t *base)

{

	unsigned long pfn, va;
@@ -509,7 +504,7 @@ void zap_low_mappings(void) 


int nx_enabled;



pteval_t __supported_pte_mask __read_mostly = ~_PAGE_NX;

pteval_t __supported_pte_mask __read_mostly = ~(_PAGE_NX | _PAGE_GLOBAL);

EXPORT_SYMBOL_GPL(__supported_pte_mask);



#ifdef CONFIG_X86_PAE
@@ -796,8 +791,7 @@ unsigned long __init_refok init_memory_mapping(unsigned long start, 
	/* Enable PGE if available */

	if (cpu_has_pge) {

		set_in_cr4(X86_CR4_PGE);

		__PAGE_KERNEL |= _PAGE_GLOBAL;

		__PAGE_KERNEL_EXEC |= _PAGE_GLOBAL;

		__supported_pte_mask |= _PAGE_GLOBAL;

	}



	/*

include/asm-x86/pgtable.h

+0 −10
Original line number Diff line number Diff line
@@ -78,19 +78,9 @@ 
#define PAGE_READONLY_EXEC	__pgprot(_PAGE_PRESENT | _PAGE_USER |	\

					 _PAGE_ACCESSED)



#ifdef CONFIG_X86_32

#define _PAGE_KERNEL_EXEC \

	(_PAGE_PRESENT | _PAGE_RW | _PAGE_DIRTY | _PAGE_ACCESSED)

#define _PAGE_KERNEL (_PAGE_KERNEL_EXEC | _PAGE_NX)



#ifndef __ASSEMBLY__

extern pteval_t __PAGE_KERNEL, __PAGE_KERNEL_EXEC;

#endif	/* __ASSEMBLY__ */

#else

#define __PAGE_KERNEL_EXEC						\

	(_PAGE_PRESENT | _PAGE_RW | _PAGE_DIRTY | _PAGE_ACCESSED | _PAGE_GLOBAL)

#define __PAGE_KERNEL		(__PAGE_KERNEL_EXEC | _PAGE_NX)

#endif



#define __PAGE_KERNEL_RO		(__PAGE_KERNEL & ~_PAGE_RW)

#define __PAGE_KERNEL_RX		(__PAGE_KERNEL_EXEC & ~_PAGE_RW)

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